var str = `<div>
<div style='border:1px solid;font-size:10px'>
1
</div>
<div  style='border:1px solid;background-color:red ; font-size:10.75px'>
2</div>
<div  style='border:1px solid;font-size:20px;display:inline-block'>3</div>
</div>`
var reg = /<[^<>]+>/g   // 获取所有的标签
let fontReg = /font-size:\s*(\d+(.[0-9]+)?)p[tx]/

var a = str.replace(reg,function(value){
  value.replace(fontReg,function(val,$1){
    console.log($1,'===',val)
  })
  return '@'
})


